PubMed Health⌕ Search

Biomedical subjects

E N Ivanov

Publications and source records attributed to E N Ivanov.

10 recordsLinked to original sources
PubMed2001

Novel interferometric frequency discriminators for low noise microwave applications.

New configurations of interferometric frequency discriminators (FD) for frequency stabilization of microwave oscillators are examined. The new FDs are arranged in single directional (SD) (patented), bi-directional (BD) (patent pending), and dual reflection (DR) (patent pending) configurations. In the SD configuration, the signals reflected off and transmitted through the resonator separately pass through different arms of the interferometer. In the BD configuration, microwaves pass in both directions through each arm of the interferometer. In the DR configuration, microwaves are reflected from the resonator as well as the compensating arm. The FD sensitivity is compared with that for the conventional interferometric FD and found to be 6 dB greater in the BD configuration. Because no circulator is required within the interferometer in either the BD or the DR FD, the discriminator's phase noise floor is not limited by the circulator contribution.

Journal Article↗
PubMed2001

Analysis of the rutile-ring method of frequency-temperature compensating a high-Q whispering gallery sapphire resonator.

The rutile-ring method of dielectrically frequency-temperature compensating a high-Q whispering gallery (WG) sapphire resonator is presented. Two and three-dimensional finite element (FE) analysis has been implemented to design and analyze the performance of such resonators, with excellent agreement between theory and experiment. A high-Q factor of 30 million at 13 GHz and compensation temperature of 56 K was obtained. It is shown the frequency-temperature compensation can occur either because the rutile adds a small perturbation to the sapphire resonator or because of a mode interaction with a resonant mode in the rutile. The characteristics of both of these methods are described, and it is shown that for high frequency stability, it is best to compensate perturbatively.

Journal Article↗
PubMed2001

Compact, high-Q, zero temperature coefficient, TE011 sapphire-rutile microwave distributed Bragg reflector resonators.

Some novel new resonator designs based on the distributed Bragg reflector are presented. The resonators implement a TE011 resonance in a cylindrical sapphire dielectric, which is confined by the addition of rutile and sapphire dielectric reflectors at the end faces. Finite element calculations are utilized to optimize the dimensions to obtain the highest Q-factors and zero frequency-temperature coefficient for a resonator operating near 0 degree C. We show that a Q-factor of 70,000 and 65,000 can be achieved with and without the condition of zero frequency-temperature coefficients, respectively.

Journal Article↗
PubMed1978

[Current problems of pathogenesis of thyrotoxicosis].

According to current concepts, thyrotoxicosis should be regarded as an autoimmune disease in which signs of a delayed type of hypersensitivity are found. The functional excitation of the thyroid gland is caused and maintained by the appearance of lymphocytes sensitized for responding to autoantigens of thyrocytes and for production of thyrostimulating autoantibodies. The course of thyrotoxicosis is aggravated by the disorder of homeostatic mechanisms which normally oppose the hyperfunction of the thyroid gland and the effect of the excess of thyroid hormones. Thus in thyrotoxicosis the disorder of immune homeostasis is accompanied by desorganization of endocrine homeostasis.

Antigen-Antibody Reactions↗
PubMedDate not supplied

[Etiology, clinical manifestations, and epidemiology in community-acquired respiratory infection in children in the Khabarovsk region].

Clinico-epidemiological analysis and etiological verification of the outbreak of respiratory infection among school children in a rural district of the Khabarovsk territory, registered in spring 1997, were made. According to clinical signs, one-third of the patients had whooping cough, while the rest of the children exhibited the signs of respiratory infection with the symptoms of longering bronchitis. A half of the children had not been vaccinated against whooping cough, as they had been given injections of adsorbed DT vaccine with reduced antigen content. Etiologically, the diagnosis of whooping cough was confirmed in 57% of the patients with 47.4% of them having Bordetella pertussis monoinfection and 52.6% having mixed infection, mainly in combination with chlamydiosis. Whooping cough took an abnormal course under these circumstances. Treatment with erythromycin produced a good effect.

Adolescent↗
PubMedDate not supplied

[Characteristics of the clinical aspects, and hormonal and immunological status of thyrotoxicosis patients with a hereditary predisposition to endocrine diseases].

The levels of triiodothyronine (T3), thyroxine (T4), TTH, STH, free triiodothyronine index T3F/T3/T4, as well as the titers of antibodies to microsome-membranous antigen and thyroglobulin, were studied in thyrotoxic patients with hereditary predisposition to endocrine diseases (thyrotoxicosis, goiter, diabetes mellitus) and in subjects without such heredity. Peculiarities of the disease development and endocrinopathy distribution among their relatives were investigated. More pronounced disorders in thyroid hormone metabolism and humoral immunity state were seen in thyrotoxic patients with hereditary predisposition to endocrine diseases. In comparison with those of the subjects without this heredity. The risk of diabetes mellitus development was detected in thyrotoxic patients predisposed to diabetes mellitus. Clinical manifestations of thyrotoxicosis (the disease severity, goiter of the IVth sage, exophthalmos) were also more evident in subjects predisposed to endocrine diseases.

Adolescent↗